The invention relates to an electric lamp comprising a lamp vessel which is closed in a gastight manner, which is provided with an end portion, which surrounds a light source, and which supports a cylindrical collar with an axis at its end portion. One or several projections of a first coupling member each grip into a respective recess of a second coupling member to couple the collar to a mounting member for fastening the lamp to a carrier, at least one of the coupling members being made of an elastic material.
Such a lamp is known from U.S. Pat. No. 5,211,472. The known lamp is an electrodeless low-pressure discharge lamp which is operated on a voltage source with a high frequency. The lamp vessel which is internally coated with a fluorescent powder, has in its end portion a cavity in which an electric coil is accommodated, which coil is supported by the mounting member. A voltage of several hundred V is present across the coil during lamp ignition. The coil generates a high electromagnetic field strength during ignition and during burning. A removal of the lamp vessel while the coil is in the energized state may be dangerous and may cause damage. Serious radio interference may occur, and the supply of the lamp may become defective owing to the removal of the load.
The first and the second coupling member in the known lamp are formed by the collar and the mounting member, respectively. The projections of the collar may, for example, each grip into an individual recess, or may alternatively cooperate with a common recess which is formed, for example, by a circumferential groove.
Although a random removal of the lamp vessel is not allowed, it is nevertheless desirable for the lamp vessel to be exchangeable, for example for replacing a defective lamp vessel, for example a damaged and leaky one, or for mounting a lamp vessel having a fluorescent powder which generates light of a different color. The known lamp for this purpose has a construction which renders it possible to remove the lamp vessel from the mounting member by means of a special tool. The user who wants to detach the lamp vessel must apply the tool to locations of the mounting member specially designed for this while at the same time rotating the collar together with the lamp vessel. It is a disadvantage that the user requires both hands for this. In addition, lamp removal may be very difficult if the lamp is badly accessible, for example because little space is available around the lamp.